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1

DDx for pneumatosis intestinalis

  • bowel necrosis
    • most important and life threatening
  • mucosal disruption
    • peptic ulcer dz
    • endoscopy
    • enteric tubes
    • trauma
    • child abuse
    • UC or Crohn's disease
  • increased mucosal permeability - often associated with immunosuppression
    • AIDS
    • organ transplantation
    • chemotherapy
    • steroid
    • graft vs host dz
  • pulmonary conditions - air from disrupted alveoli dissect along the bronchopulmonary interstitium and retroperiteoneum along the visceral vesels to the bowel wall
    • COPD
    • asthma
    • mechanical ventilation
    • ptx
    • pneumediastinum

2

Cystic pneumatosis

vs 

Linear pneumatosis

  • cystic pneumatosis -
    • well-defined blebs or grapelike clusters of spherical air collections in the subserosal region
    • usually benign
    • these air cysts may rupture and result in benign pneumoperitoneum
  • linear pneumatosis -
    • streaks of gas within and parallel to the bowel wall
    • maybe benign or ischemic causes

3

Sigmoid volvulus

vs

Cecal volvulus

  • sigmoid volvulus
    • point towards LLQ
    • proximal colon and small bowel are dilated
  • cecal volvulus
    • point towards RLQ
    • proximal small bowel dilated
    • distal colon collapsed
    • vs cecal bascule - folding rather than a twisitng of a mobile cecum

4

Courses of pelvic muscles

iliopsoas

piriformis

pelvic diaphragm

  • Iliopsoas
    • psoas m. joins the iliacus m.
    • lesser trochanter
  • Piriformis
    • anterior sacrum to
    • greater trochanter
  • Pelvic diaphragm
    • anterior - levator ani
    • posterior - coccygeus

5

Level of aortic bifurcation

Level of iliac artery bifurcation

  • Aorta bifurcates into common iliac arteries at the level of iliac crest
  • Common iliac arteries bifurcates at the level of pelvic brim - marked on CT by the transition b/t the convex sacral promontory and the concave sacral cavity 

6

Denonvillier's fascia

tough barrier b/t the prostate and rectum

preventing spread of disease from one organ to the other

7

Cervical malignancies

  • 85% - squamous carcinoma
  • 15% - adenocarcinoma
  • low attenuation or isoattenuating compared to normal cervix - reduced vascularity, necrosis or ulceration
  • II-b - invasion of the parametrium - no longer surgical candidate

8

Endometrial malignancy

Hematogenous spread to lung, bone, liver, and brain is much more common with endometrial cancer than cervical cancer

9

In adnexal torsion, the uterus is usually deviated to the affected side

In adnexal torsion, the uterus is usually deviated to the affected side

10

Trough sign

Vertical lucency 

indicates an impaction from posterior shoulder dislocation

11

When disc material migrates from the parent disc, it is termed a "sequestered" or "free fragment"
:

When disc material migrates from the parent disc, it is termed a "sequestered" or "free fragment"

12

By noting the density differences b/t the "mass" and the thecal sac

By noting the density differences b/t the "mass" and the thecal sac

  • if "mass" is denser than thecal sac - it is a bulged disc or sequestered disc
  • if "mass" is isodense as the thecal sac - it is a Tarlov cyst/perineural cyst or conjoint nerve root

13

Types of spinal stenosis

Types of spinal stenosis

  • central canal stenosis
  • lateral recess stenosis
  • neuroforaminal stenosis

14

Central canal stenosis

  • most useful CT criteria for diagnosing central canal stenosis - obliteration of epidural fat & flattening of the thecal sac
  • most common cause of central canal stenosis - fact degenerative disease 
  • other causes
    • hypertrophy of ligamentum flavum - actually "buckling"
    • paget's disease
    • DISH with ossification of the posterior longitudinal ligament

15

Neuroforaminal stenosis

Causes of neuroforaminal stenosis

  • degenerative joint disease
    • osteophytes arising from the vertebral body or the facet
  • disc protrusion
  • postop scar 

16

DDx of diseae entities that have sequestrum

DDx of diseae entities that have sequestrum
 
  • osteomyelitis
  • EG
  • desmoid tumor
  • malignant fibrous histiocytoma

17

Ortner Syndrome

Cardiovocal hoarseness

  • In this syndrome, the LRLN is injured as it loops around the aorta at the aortopulmonary window and along the outer side of the ligamentum arteriosum due to compression or traction caused by changes in the anatomy of the heart or great vessels.
  • The left vagus nerve gives rise to the LRLN at the level of the aortic arch, which supplies muscles of the left larynx except the cricothyroid muscle (supplied by the superior laryngeal nerve).
  • In isolation, laryngeal findings cannot differentiate RLN palsy from high vagal lesions; however, coincident pharyngeal constrictor atrophy and ballooning of the pharyngeal wall suggest pharyngeal plexus injury due to brain stem or central vagal nerve lesions. Moreover, coincident palsies/atrophy of the trapezius and sternomastoid muscles indicate associated spinal accessory nerve injury with involvement at the jugular foramen or high carotid sheath (above the level of the posterior belly of the digastric muscle).
  • Evaluation of the heart, aorta, and supra-aortic thoracic vessels to rule out compression or traction along the thoracic course of RLNs should be part of screening for possible underlying causes of RLN paralysis.

18


"out of proportion TO..."


"Out of proportion TO..."

19

Fracture of the lateral talar process

“snowboarder fracture”

  • often missed - anterolateral ankle pain related to such a fracture often mimics that of an anterior talofibular ligament sprain. Unfortunately, there is a high likelihood of developing osteoarthritis following lateral talar fractures, thus reinforcing the need for a correct diagnosis and optimal management.
  • the lateral process is often identified inferior to the tip of the fibula. Any lucency, as in this index case, should prompt the diagnosis. Detailed evaluation of a well-positioned lateral radiograph with regard to the the angle of Gissane should demonstrate a well-defined smooth “V” shape of the lateral process.
  • CT should be suggested for further evaluation if radiographic findings are equivocal, as well as to define the full extent of the fracture.
  • lateral process fracture staging system (Hawkins) is:

    Type I: Nonarticular chip fracture
    Type II: Intra-articular, single fracture line
    Type III: Intra-articular, comminuted

20

Normal and abnormal ankle xrays

Lateral talar process fracture

21

Gissane's angle

Gissane's angle

22

Left PICA stroke

ALWAYS look at the cerebellar hemispheres!

REMEMBER:

Cerebellar stroke - symptoms are IPSILATERAL!!!

Fibers have already crossed over!

23


When describing perianal abscess, it is important to differentiate b/t

intra-sphincteric

vs

extra-sphincteric

abscess


When describing perianal abscess, it is important to differentiate b/t

intra-sphincteric

vs

extra-sphincteric

abscess

24

Cause of post aneurysm coiling headache?

  1. RARE - delayed rupture of the aneurysm, which may have been ruptured partially during the coiling process
  2. COMMON - thrombosis of the aneurysm inciting an inflammatory response

25

The RLN arises from the vagal trunk in the thorax. On the left, the RLN arises at the level of the aortic arch; it crosses the aortic arch and hooks around the ligamentum arteriosum. On the right side, the RLN hooks around the first part of the subclavian artery, then ascends in the groove between the trachea and the esophagus. Because of its longer thoracic course, LRLN palsy is more common than right RLN palsy. The left RLN comes into close contact with left lung apex, aorta, pulmonary artery, ligamentum arteriosum, trachea, esophagus, and mediastinal lymph nodes and accordingly is vulnerable to compression or traction by pathological conditions of any of these structures.

The RLN arises from the vagal trunk in the thorax. On the left, the RLN arises at the level of the aortic arch; it crosses the aortic arch and hooks around the ligamentum arteriosum. On the right side, the RLN hooks around the first part of the subclavian artery, then ascends in the groove between the trachea and the esophagus. Because of its longer thoracic course, LRLN palsy is more common than right RLN palsy. The left RLN comes into close contact with left lung apex, aorta, pulmonary artery, ligamentum arteriosum, trachea, esophagus, and mediastinal lymph nodes and accordingly is vulnerable to compression or traction by pathological conditions of any of these structures.

26

The right and left RLNs supply all the muscles of the larynx except the cricothyroid muscle as well as sensory supply to the larynx below the VCs and the upper part of trachea (supplied by the superior laryngeal nerve).

The right and left RLNs supply all the muscles of the larynx except the cricothyroid muscle as well as sensory supply to the larynx below the VCs and the upper part of trachea (supplied by the superior laryngeal nerve - also a branch of the vagus nerve).

27

Left atrial, aortic, or pulmonary artery enlargement is encountered in various congenital heart diseases and can result in compression of the LRLN. 

Aneurysms of different etiologies, direct injury in ductal ligation, or transcatheter closure of patent ductus arteriosus or upon repair of aneurysms are all associated with risk of LRLN palsy. Primary and secondary pulmonary hypertension, with enlargement of the pulmonary artery (as in our case) are also reported to cause LRLN palsy. Some patients with arteriosclerotic heart diseases can suddenly suffer LRLN paralysis due to rapid onset of left ventricular failure with sudden pulmonary hypertension with acute dilatation of the pulmonary vessels. This phenomenon has been ter­med dynamic dilation.

28

CT findings of VC paralysis include decreased volume of the thyroarytenoid and posterior cricoarytenoid muscles due to denervation atrophy, anteromedial rotation of the arytenoid cartilage, dilation of the ipsilateral laryngeal ventricle, pyriform sinus and vallecula, and thinning and medialization of the ipsilateral aryepiglottic fold. On coronal images, pointing of the VC and flattening of the subglottic angle are seen. 

CT findings of VC paralysis include decreased volume of the thyroarytenoid and posterior cricoarytenoid muscles due to denervation atrophy, anteromedial rotation of the arytenoid cartilage, dilation of the ipsilateral laryngeal ventricle, pyriform sinus and vallecula, and thinning and medialization of the ipsilateral aryepiglottic fold. On coronal images, pointing of the VC and flattening of the subglottic angle are seen. 

29

Acute Disseminated Encephalomyelitis

ADEM

  • ADEM is an autoimmune demyelination disorder
  • occurs 5 - 14 days after a viral illness or vaccination
  • peak age 3-5 y/o
  • The classic appearance is multifocal T2 and FLAIR hyperintensities in the brain and spinal cord (esp in the dorsal white matter) with multifocal neurologic deficits.
  • The appearance of ADEM is often identical to multiple sclerosis, although ADEM is a monophasic self-limiting disorder.
  • Steroids and/or plasmapheresis is the treatment of choice.

30

Pleural mets secondary to thymoma

"Drop mets"

Dry - no associated pleural effusion